Aeroflot customer services are pretty useless.
If you're not getting anything useful from them, I suggest sending a notice before action letter to Aeroflot's UK registered address.
If this doesn't solicit an acceptable response, start MCOL action.
Also, for EU261 compensation, your arrival time to Moscow is irrelevant. What counts is your scheduled arrival time in Ufa and your actual arrival time in Ufa.